Hellmig



March 31, 964 E. HELLMIG 3,127,268

TONE CORRECTION OF PHOTOGRAPHIC IMAGE Filed March 15, 1956 b FIG] L06l-T a d z- S 3 F/G.2 g

E 4'00 500 600 my LOG l-T INVENTOR. EHRHARD HE LLM/G A T TORNEYS UnitedStates Patent TGNE CGRRECTKGN OF PHQTfif-RAEPl-HQ llviAQ-E EhrhardHelhnig, Levcrhnsen, Germany, assignor to Agin Alrtiengesellschait,Leverhuscn, Germany, a corporation of Germany Filed Mar. 155, i955, Ser.No. 57l,7*3 (ll-aims priority, application Germany Mar. 19, 1955 8Claims. ill. 96-44) The present invention relates to a process for thetone correction of black-and-White or monochromatic photographic images.

It is known that black-and-white or monochromatic photographic images,particularly in the reproduction art (also color separation records) areaffected by so-called tone defects, which are shown in the defectiveportrayal of the high-lights and/or shadows. Processes for overcomingthese defects are known; the essence thereof consists in the combinationof the normal print requiring correction with a separate black-and-whiteimage or print of the same original, which contains only the correctionof a certain type of tones or or" several types of tones simultaneously,it being possible for several tone masks, for example high light masksand shadow masks, to be combined in one combined tone mask or to bepresent as separate individual masks (compare German patentspecifications 505,447, 529,371, 715,654, 731,244, 888,- 362, and U8.patent specification 2,544,910).

The production of a tone separation record in the correct density iscombined with certain difficulties and. represents a routine operation,since it depends on the subject of the exposure, for example, itsnature, brightness or gradation; therefore such a mask must be repeatedor after-treated in many cases, for example if it has been too weaklyexposed or developed too flatly.

It has now been found that the tone correction of black-and-white ormonochromatic images can be essentially simplified and the saiddisadvantages can be overcome if the black-and-white or monochromaticimages are combined with a colored tone-separation record and copied. Bythis means, the tone mask can be made effective at full strength ofhardness, or it can have no efiect at all or be effective with allpossible intermediate stages, depending on the choice of the copying orexposure light. It is thus possible for the effect of a mask which isperhaps too strong, too hard or perhaps over-exposed to be reduced asdesired, without having to effect a reduction of the mask by chemicalafter-treatment.

Any desired color can be chosen for the tone mask, provided only thatthis color has a more strongly absorbing and a less strongly absorbingrange within the spectrum, that is to say, is not neutral grey in color.Particularly suitable are such colors in which the difference betweenmaximum and minimum spectral absorption is as great as possible andwhich therefore are especially saturated and bright, as is the case forex ample with colors such as magneta, blue-green, red, green or violet,since with these particularly large modifications in the hardness of themask are possible. Less pronounced colors can if necessary also be used,depending on the position of the practical case in this respect.

The process is to be explained by way of example by reference to theaccompanying figures.

For example, if the mask is produced in the color yellow, this has itsgreatest hardness or eificiency in connection with blue printing light,as represented by curve a in FIGURE 1. With green printing light, on theother hand, it is without any effect, since the color yellow ispermeable to green light (FIGURE 1, curve (I). The same also applies forred or yellow light or green plus red light. By using mixed blue andgreen "ice light in the printing of the yellow-colored tone-separationrecord, it is then possible for the degree of hardness of thetone-separation record to be adjusted as desired, depending on the ratiobetween the two colors blue and green or red (FIGURE 1, curves 1) andc), it being presupposed that the light-sensitive material on to whichthe mask is to be further copied is also sensitive to green and/ or redlight as well as to blue light.

Examples for corresponding color filters, namely blue and green filters,are represented in FIGURE 2 in the form of spectral transmission curvesa to d. The successive exposure with suitable amounts of blue and greenlight is equivalent to the exposure through such a filter.

The co-operation of a normal continuous tone image and a color toneseparation record when they are printed after being brought in printingregister is shown in FIG- URE 3. The eificacy of the yellow toneseparation records according to FlGURES lad in the continuous tone imageis clearly apparent in this FIGURE 13.

The invention is not limited to separate tone separation records; such acolor tone separation record can also be inseparably combined with thenormal-tone image. This case can be achieved for example by a suitabletwolayer material; in this connection, the layers can either be cast oneabove the other, if necessary separated by a filter layer, or forexample for the purpose of making possible separate treatments (etching,developing), they can also be arranged on different sides of thesupport. In order that it may be possible for the separate layers of theprint to be exposed independently of one another, these layers can besensitive for differently colored light. For example, thelight-sensitive half-tone layer can be green-sensitive for thenormal-tone image, while the layer for the tone separation record can beblue-sensitive.

In a further modification of this embodiment, the normal-tone image andthe tone separation record are preferably differently colored. Due tothe kind of light used with the printing of such a material, each of thetwo images can be independently influenced, so that both the hardness ofthe continuous tone image and the hardness of the mask can be influencedas required and independently of one another. It is thus possiblewithout special technical aids to carry out a socalled additive masking,such as that which forms the basis, for example, of the knowntone-separation process according to Person. The only condition to beobserved in the process is that the two dyestuffs have separateabsorption and permeability zones in the spectrum, although a partialoverlapping of these zones does not prevent the process being carriedinto efiect. Such pairs of dyestuffs are sufiiciently Well known fromthree-color photography on multi-layer material: for example,yellow/blue green or yellow/magenta or magneta/blue-green.

For example, if the normal-tone layer is magenta and the tone separationrecord is yellow, the former can be copied with green light and thelatter with blue light separately from one another on to anorthochromatic material, which is sensitive to blue and green.

The following additional embodiments are also possible: Aslight-sensitive record material, a silver halide layer is used whichcontains a comparatively insensitive color coupler. After the exposureand the color development of such a material, a black-and-Whitecontinuous tone image is formed, this image representing the normal toneimage and being super-imposed by a color image which is iormed only atthe places where the exposure is high ad which represents thetone-separation record. If necessary, the black-and-white continuousimage can be further intensified by using a non-color-couplingdeveloper, used separately or simultaneously in admixture with the colordeveloper.

enemas The coloring of the masks can take place according to anysuitable processes; color development, silver colorbleaching processesand mordant processes are to be mentioned as examples thereof.

The same effect can be produced by the exposed lightsensitive materialbeing developed with a black-and-white developer of such a qualitativecomposition that a colored image designated as a so-called residualimage is simultaneously formed in the higher densities (highlights) inaddition to the silver. Such developers and developer compositions aresufiiciently well known. Developers suitable for these purposes are:alkaline aqueous solutions of developer substances of the dihydroxyandtrihydroxy benzene group, such as for example pyrocatechol,hydroquinone, chlorohydroquinone, pyrogallol.

*Instead of the black-and-white half-tone image, it is again alsopossible have a colored image, it being possible for the colors of thetwo images again to show a common absorption range (subtractive masking)or separate absorption ranges.

Example 1 On a transparent support there is coated a silverbromide-gelatine emulsion, which is sensitized for the green part of thevisible spectrum and which contains a conpler -for the production of amagenta color image by the process of color forming development g. of1(4'- phenoxy 3 sulphophenyl)-3-stearyl-5'pyrazolone per 1 liter).

On this layer a second silver halide layer is coated which is notoptically sensitized and which has a sensitivity that is of that of theinner layer. into the outer layer a coupler for the production of ayellow color image by the process of color forming development isincorporated (15 g. ofp-stearoyl-aminobenzoyl-acetanilide-3,5-dicarboxylic acid per 1 liter ofemulsion).

This material is exposed in a camera to a black-andwhite half-toneimage, thereafter it is developed for 5 minutes in an ordinary colorforming developer solution (p-diethyl-aminoaniline being the developersubstance) washed, bleached and fixed and finally washed.

The emulsions for said two-layer material must fulfill the followingconditions: The magenta image produced in the inner layer (continuoustone image) should have a gradation of 1.3 when measured behind a greenfilter the transmittance of which lies in the region between 500 and 600mu, whereas the yellow image of the upper layer (tone-mask) should havea gradation of 3.2 when measured behind a blue filter, the transmittanceof which lies between 400 and 500 m This image, representing a combinedcontinuous tone image and masking image is printed onto anorthochromatic silverhalide layer in two steps, for the first step blueprinting light and for the second step green printing light being used.The eficiency of the masking image may be varied by varying theproportion of exposure times behind the blue and green filtersrespectively.

The same etfect may be achieved if the same two-layer material is usedwhich, however, does not contain a coupler in the inner layer. In thiscase the material is not bleached after development but only fixed,whereby a silver image and a silver plus dyestuif image are obtained inthe inner and outer layer respectively.

Example 2 A -black-and-white continuous tone image on a paper support isexposed to a silver halide layer coated on a transparent support andprocessed to a blaclt-and-white silver image with a contrast of 1.4.

Thereafter a second exposure is made on another sil ver halide layer ofthe same type as before, however, the exposure is made so short thatonly the high-lights of the original are reproduced. After developmentin an ordinary color forming developer containing a coupler for theproduction of a magenta color image washing,

fixing, bleaching, washing and drying a high light tone mask isobtained.

Both images are brought in register and the combined images are printedonto an orthochromatic silver halide layer as disclosed in Example 1.

Example 3 A multi-color negative is printed through a green filter ontotwo sheets of a photographic material consisting of an orthochromaticsilver halide layer coated on a transparei support. The exposure timesare the same as in Example 2. For the development of the masking image adeveloper is used which contains a coupler for the production of a cyanimage, whereby a cyan shadow mask is obtained in the one material,whereas a blackand-white half-tone image is otbained in the othermaterial.

The two images, after being brought in register, are printed through ascreen onto a panchromatic silver halide layer, the exposure being madethrough a red filter (transmission above 580 mg) and then through agreen filter (transmission about 480 to 600 m The screened print isdeveloped, fixed, Washed and dried. It may be used as a copy for theproduction of a printing plate for printing the red partial image in amulti-color printing process.

Example 4 A black-and-white diapositive having a contrast of 1.5 isprinted by means of a light source emitting ultra-violet light onto alight sensitive diazo layer as it is put on the market by the firm Katie& Co. under the trade name Ozachrom. The exposure is such that afterdevelopment a yellow image of the high lights only is obtained (shadowmask). The diapositive and the yelloW shadow mask are brought inregister and printed onto a carbon tissue (pigment paper).

What I claim is:

l. The process of producing tone-corrected photographic copies of anoriginal which comprises providing a normal monochrome photographicimage of said origi nal, which image is defective in that it has tooshort a range of gradation in the highlights of the original, providinga dyestuff image of essentially only the highlights of the original,having the same sign as the monochrome image, and having a spectralrange in one color portion of the spectrum, which portion is differentfrom that in which there is any maximum absorption of the monochromeimage, combining the images, printing said combined images onto alight-sensitive silver halide layer by means of a printing lightselected to be absorbed by both of the images, and adjusting theprinting light to cause the monochrome image to be printed and to causethe dyestuff image to be printed to a predetermined degree along withthe monochrome image and provide print highlights with a steepergradation than from the monochrome image alone.

2. Process according to claim 1, wherein the dyestut'f image isinseparably combined with the detective photographic image.

3. Process according to claim 1, wherein the dyestufl image and themonochrome separate image are carried by supports.

4. Process according to claim 2, wherein the detective image and thedyestuif image are contained in a common layer.

5. Process according to claim 1, wherein the defective image is ablack-and-white image.

6. Process according to claim 1, wherein the defective image is a blacland-white image and the dystufr" image is combined with a correspondingsilver image.

7. Frocess according to claim 1, wherein the dyestuff image is acolor-developed image.

8. Process according to claim 1, wherein the printing 5 6 of the normalimage and of the dyestufi image is carried 2,294,981 Hanson Sept. 8,1945 out in separate steps. 2,455,849 Yule Dec. 7, 1948 2,533,452 Glasoeet a1 Dec. 12, 1950 References Cited in the file of this patent2,544,910 Yule Mar. 11, 1951 UNITED STATES PATENTS 5 2,737,457 ChildressMar. 6, 1956 1,954,335 Seymour Apt 10, 1934 2,848,326 Whltmore 19, 19582,193,931 Michaelis Mar. 19, 1940 OTHER REFERENCES 2,241,413 Mich'flelisY 13, 1941 Niblette: Photography-Its Materials and Processes 2,338,661M9rrls T 4, 1944 m fifth ed., 1952, pages 480-481. (Copy in Div. 60.)2,347,119 Mlchaells P 18, 1944 Lester: Photo Lab Index, vol. 2, 1952,pages 16-87 2,378,213 Glasoe J n 12, 1945 n 1 3, (Copy i 0.

1. THE PROCESS OF PRODUCING TONE-CORRECTED PHOTOGRAPHIC COPIES OF ANORIGINAL WHICH COMPRISES PROVIDING A NORMAL MONOCHROME PHOTOGRAPAHICIMAGE OF SAID ORIGINAL, WHICH IMAGE IS DEFECTIVE IN THAT IT HAS TOOSHORT A RANGE OF GRADATION IN THE HIGHLIGHTS OF THE ORIGINAL, PROVIDINGA DYESTUFF IMAGE OF ESSENTIALLY ONLY THE HIGHLIGHTS OF THE ORIGINAL,HAVING THE SAME SIGN AS THE MONOCHROME IMAGE, AND HAVING A SPECTRALRANGE IN ONE COLOR PORTION OF THE SPECTRUM, WHICH PORTION IS DIFFERENTFROM THAT IN WHICH THERE IS ANY MAXIMUM ABSORPTION OF THE MONO-